Adds alias __errno to linker file fixed link, need to understand why.

src/modules/px4iofirmware/CMakeLists.txt

@@ -110,6 +110,7 @@ add_dependencies(firmware_io_nuttx
 	nuttx_export_${config_io_board}
 	msg_gen
 	io_prebuild_targets
+	mixer_gen
 	)
 
 set(nuttx_export_dir ${CMAKE_BINARY_DIR}/${config_io_board}/NuttX/nuttx-export)

src/modules/systemlib/mixer/CMakeLists.txt

@@ -37,6 +37,9 @@ add_custom_command(OUTPUT mixer_multirotor.generated.h
 	COMMAND ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/multi_tables.py
 	> mixer_multirotor.generated.h)
 
+add_custom_target(mixer_gen
+	DEPENDS mixer_multirotor.generated.h)
+
 px4_add_module(
 	MODULE modules__systemlib__mixer
 	SRCS